At hydrocarbon facilities, crude oil is produced from oil wells and is subsequently transported to a gas-oil separation plant (GOSP) for treatment. Once gas is separated from the crude oil at the GOSP, the crude oil is pumped from the GOSP to tanks for storage and export. Typically, water is mixed with crude oil flowing through pipes as the crude oil leaves a GOSP. Once the crude oil is stored in a tank, the mixture of crude oil and water will separate after a certain settling time. The specific weight and the density of crude oil is less than that of water. Therefore, the water will settle to a bottom region of the tank, and the crude oil will settle on top of the water. A level of the interface between the water and the crude oil will depend on amounts of crude oil and water within the tank. For crude oil within a tank to be sold, a water cut of the tank (for example, the volume of water present in the tank) must be below an acceptable threshold volume. Thus, the volume of water above the threshold volume is drained, and the crude oil remaining in the tank is subsequently shipped. The threshold volume typically corresponds to a certain height of a water level above a floor of the tank.
In order for excess water to be drained from the tank, the water cut in the tank must first be determined. Conventionally, a dip gauge is used to determine a water cut of a tank. In use, an operator climbs to a roof of the tank and drops a dip gauge into the tank while holding on to an end of a deployment cable to which the dip gauge is attached. The dip gauge includes a base material that changes color upon chemically reacting with water. Accordingly, once the dip gauge reaches the bottom of the tank, a height of the dip gauge at which the base material changes color reflects a water level in the tank. The operator pulls the dip gauge from the tank and measures a length of a reacted portion of the dip gauge, where each increment of length of the reacted portion corresponds to a certain volume of water in the tank. Deploying a dip gauge to measure the water cut is associated with several operational, health, and safety risks.